Volcanic influence of Mt. Fuji on the watershed of Lake Motosu and its impact on the lacustrine sedimentary record
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Article de revue
Ce document a été publié dans
Sedimentary Geology. 2018-01, vol. 363, p. 200 - 220
Résumé en anglais
Lacustrine sediments are particularly sensitive to modifications within the lake catchment. In a volcanic
area, sedimentation rates are directly affected by the history of the volcano and its eruptions. Here, we ...Lire la suite >
Lacustrine sediments are particularly sensitive to modifications within the lake catchment. In a volcanic
area, sedimentation rates are directly affected by the history of the volcano and its eruptions. Here, we investigate
the impact of Mt. Fuji Volcano (Japan) on Lake Motosu and its watershed. The lacustrine infill is
studied by combining seismic reflection profiles and sediment cores. We show evidence of changes in sedimentation
patterns during the depositional history of Lake Motosu. The frequency of large mass-transport
deposits recorded within the lake decreases over the Holocene. Before ~8000 cal yr BP, large sublacustrine
landslides and turbidites were filling the lacustrine depression. After 8000 cal yr BP, only one large
sublacustrine landslide was recorded. The change in sedimentation pattern coincides with a change in sediment
accumulation rate. Over the last 8000 cal yr BP, the sediment accumulation rate was not sufficient
enough to produce large sublacustrine slope failures. Consequently, the frequency of large masstransport
deposits decreased and only turbidites resulting from surficial slope reworking occurred. These
constitute the main sedimentary infill of the deep basin. We link the change in sediment accumulation
rate with (i) climate and vegetation changes; and (ii) theMt. Fuji eruptions which affected the LakeMotosu
watershed by reducing its size and strongly modified its topography. Moreover, this study highlights that
the deposition of turbidites in the deep basin of Lake Motosu is mainly controlled by the paleobathymetry
of the lakefloor. Two large mass-transport deposits, occurring around ~8000 cal yr BP and ~2000 cal yr BP
respectively, modified the paleobathymetry of the lakefloor and therefore changed the turbidite
depositional pattern of Lake Motosu.< Réduire
Mots clés en anglais
Lake Motosu
Mount Fuji
Volcano
Mass-transport deposits
Turbidites
Sediment accumulation rateLake
Motosu
Mount Fuji
Volcano
Mass-transport deposits
Turbidites
Sediment accumulation rate